[STCrowley]

My big advice is to always roll-play the situation. If they don't know what the topics will be, give them two or three that you make up, and make them treat them like the 'real thing.'

The hardest thing about doing this, I've found, is that it's difficult to make them take the exercise seriously. I mean, my students will turn the roll play into an abstraction and say 'but in the real thing, I'd do it differently.' It's hard for me to get them to treat me--who they've come to see as a friend--as the test giver.

The other challenge is more for me: I have to stop worrying about vocabulary (because it's really too late to get into that, and because that's not what it's about) and to try and be critical of how they do with their body language and voice.

My biggest advice is this: find a copy of the criteria, ask your students if they know what the topics are, and then drill them.

Another thing: if they have to transition on their own, I'd give them one topic, make them find a completely different topic and say "Okay, how can you transition from 'electronics' to 'dairy production?')

Hope that helps!